Baffle type muffler with a plurality of outlet conduits



Nov. 24, 1953 R. B. BOURNE ET AL BAFFLE TYPE MUFFLER WITH A PLURALITY OF OUTLET CONDUITS Filed April 14, 1951 Fig. 3

a 6 n r U 0 B B d n M O R John P. Tyskewicz inventors y Al orney Fig. 4

Patented Nov. 24, 1953 BAFFLE TYPE MUFFLER WITH A PLURAL- ITY OF OUTLET CONDUITS Roland B. Bourne, West Hartford, and John P. Tyskewicz, Hartford, Conn., assignors to The Maxim Silencer Company, Hartford, Conn., a corporation of Connecticut Application April 14, 1951, Serial No. 221,101

4 Claims. 1

This invention relates to silencers intended primarily for use in compact quarters to silence the exhaust of an internal combustion engine having up to several hundred horse power, although it is not restricted to that field. In uses such as that, however, the flow of exhaust gas is extremely large, and particularly where space is restricted the problem of keeping back pressure within permissible limits is difficult of solution. The object of the present invention is to provide a silencer which will preserve an acceptable silencing action without raising the back pressure to a point where the operation of the engine will be seriously affected.

The invention will now be described with reference to the accompanying drawing, in which Fig. 1 is a median section through a silencer embodying the invention in its preferred form, taken on line |--l of Fig. 2;

Fig. 2 is a transverse section taken on line 22 of Fig. 1;

Fig. 3 is a transverse section taken on line 3-3 of Fig. 1; and

Fig. 4 is a fragmentar section similar to a portion of Fig. 1 but showing a modification.

The silencer in its preferred form has but a single chamber into which the inlet and outlet conduits enter. A novel feature is the way in which the gas stream is conducted from the inlet conduit to the interior of the chamber so as to cause a minimum of back pressure to be exerted on the entering gases. The casing H1 is cylindrical in form (using the term cylindrical in its broad sense) and is preferably substantially elliptical in cross section. The ends of the casing are closed by headers I I and I2. A pair of inlet conduits l3 and 14 enter the casing substantially in the line of the minor axis of the ellipse, and terminate with open ends substantially flush. with the casing wall. A series of four outlet conduits l5, l6, l1 and i8 enter the casing parallel to the major axis of the ellipse and terminate with open ends somewhat past the central longitudinal plane of the casing. These conduits are kept relatively small in diameter by increasing their number to give the requisite total cross section for the passage of the amount of gas delivered by the engine, and are located as far from the inlet conduits as is practicable. The open ends of the outlet conduits are flared outwardly as at I9 to reduce entrance losses and thus contribute to the reduction in back pressure, and are provided with anti-resonance holes 20 as described in Bourne Patent 2,297,046, September 29, 1942.

Above the inlet conduits, and substantially parallel to the wall of the casing, is a transversely curved plate 2| extending from one end to the other of the casing. Its transverse curvature is preferably on a radius slightly greater than that on which the adjacent wall of the casing is formed, so that the edges of the plate are closer to the casing wall than its central portion. For convenience in manufacture the plate 2| is mounted on end supports '22, 23 shaped tofit the inner surface of the casing wall and preferably secured to it as by tack welding. The space 24 between the plate and the casing acts as a coupling slot between the inlet conduits and the interior 25 of the casing, and has several functions. The plate itself acts as a baffle keeping the gases from passing directly into the outlet conduits. The slot opens at 26 and 21 into the interior 25 of the casing on both sides of the inlet conduits in a direction peripherally of the easing, and at some distance from the conduits. It also extends between the inlet conduits and between them and the ends of the casing. There is thus a considerable surface, both of the plate and the casing, with which the gas makes contact; and due to this and to the relatively close spacing between the plate and the casing (preferably about one-third of the inside diameter of the inlet conduit) considerable high frequency attenuation takes place as the exhaust gas passes through the slot. This of itself decreases the back pressure, and the effect is aided by the expansion caused by the fact that the area of the slot met by the gas (not the depth of the slot) is constantly increasing as the gas moves outwardly from the inlet conduit. In order to strengthen the plate 2| and to support the latter near its center a segment of a ring 28 is secured to the plate as by welding, and as shown in Fig. 3 extends beyond the plate so that is can be secured to the casing at 29.

Fig. 4 shows a modification in which each pair of the four outlet conduits has been replaced by a conduit 30 of larger size and of flattened cross section to keep it as far away from the inlet conduit as possible.

What we claim is:

1. A silencer comprising a cylindrical shell. headers closing the ends of the shell to form a single chamber, a plurality of open-ended inlet conduits entering the cylindrical shell substantially radially at one side thereof and terminating substantially flush with the shell, a plurality of open-ended outlet conduits positioned along a line remote from the inlet conduits and entering the shell in a direction substantially at right angles to the inlet conduits, and a curved plate within said chamber covering the open ends of the inlet conduits, extending from one end header substantially to the other, and spaced from the inside of the shell a distance on the order of one third of the diameter of the inlet conduits to provide a passage between the inlet conduits and the interior of said single chamber.

2. A silencer comprising a cylindrical shell, headers closing the ends of the shell to form a single chamber, at least one open-ended inlet conduit entering the cylindrical shell at one side thereof, at least one open-ended outlet conduit entering the cylindrical shell at a point remote from the inlet conduit, and a plate substantially parallel to the shell, covering the open end of the inlet conduit and extending from one header to the other and circumferentially of the shell in both directions from the inlet conduit to form a narrow passageway opening into said single chamber in zones on each side of the inlet conduit between it and the outlet conduit, said plate being convex in a direction towards the inlet conduit.

3. A silencer comprising a shell in the form of a cylinder of substantially elliptical crosssection, headers closing the ends of the shell to form a single chamber, at least one open-ended inlet conduit entering said shell in the direction of the minor axis of the ellipse and terminating substantially flush with the shell, at least one open-ended outlet conduit entering the shell in a direction parallel to the major axis of the ellipse and remote from said inlet conduit, and a plate parallel to the shell, covering the open end of the inlet conduit and extending from one header to the other and circumferentially of the shell in both directions from the inlet conduit to form a narrow passageway opening into said single chamber in zones on each side of 4 the inlet conduit between it and the outlet conduit, said plate being convex in a direction towards the inlet conduit.

4. A silencer comprising a shell in the form of a cylinder of substantially elliptical crosssection, headers closing the ends of the shell to form a single chamber, at least one open-ended inlet conduit entering said shell in the direction of the minor axis of the ellipse and terminating substantially flush with the shell, at least one open-ended outlet conduit entering the shell in a direction parallel to the major axis of the ellipse and remote from said inlet conduit and extending past said minor axis to a point in adjacency to the inside wall of the shell, and a plate parallel to the shell, covering the open end of the inlet conduit and extending from one header to the other and circumferentially of the shell in both directions from the inlet conduit to form a narrow passageway opening into said single chamber in zones on each side of the inlet conduit between it and the outlet conduit, said plate being convex in a direction towards the inlet conduit.

ROLAND B. BOURNE. JOHN P. TYSKEWICZ.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,078,754 Day Apr. 27, 1937 2,297,046 Bourne Sept. 29, 1942 2,337,299 Noblitt et a1 Dec. 21, 1943 2,457,890 Hedrick Jan. 4, 1949 2,513,229 Bourne et al June 27, 1950 2,537,203 Bourne et al. Jan. 9, 1951 FOREIGN PATENTS Number Country Date 56,216 Switzerland June 15, 1911 

